A loupe, a magnet and a test kit each answer a narrow question, and none of them proves a piece is genuine. A loupe lets you read stamps and see construction. A magnet rules some things out. A test kit gives a better hint about metal but involves corrosive liquids and still leaves doubt. Used together and for what they do well, they help you decide whether a piece deserves a closer look from a professional, not whether it is worth a specific amount.
Our thrift store jewelry guide shows what to look for in the bin. This post reviews the tools themselves and their limits, so you spend money on the right ones and do not treat any single result as a verdict.
The Loupe: Your First and Best Tool
A jeweler's loupe is a small magnifier, and it is the one tool every jewelry sourcer should own. Its main job is reading marks. Tiny stamps inside a ring band, on a clasp or on the back of a pendant often name the metal, the maker or a country of origin, and they are hard to read with the naked eye.
A loupe also shows construction. Look at solder joints, how stones are set, whether a surface is worn through to a different color underneath, and whether the finish looks uniform. Worn edges that reveal another metal can point to plating, which is a very different item from solid metal.
Choose a loupe that is comfortable to hold close to your eye, with a lens that is clear to the edge. A small built-in light is useful in dim thrift store aisles. Our garage sale flipping toolkit lists other pocket items worth carrying.
Jeweler's Loupe with Built-In Light
Pick a comfortable magnification and a lens that is clear across the field. A small light helps in dim aisles.
Search on Amazon → Search on eBay →As an Amazon Associate, we earn from qualifying purchases at no extra cost to you. We only recommend gear we’d buy ourselves.
What a Stamp Does and Does Not Tell You
Marks help but are not proof. The FTC's Jewelry Guides, which cover how metal quality is described in sales, explain that a karat mark states the fineness of a gold alloy and that "sterling" refers to silver of at least 925 parts per thousand. They also treat terms like gold plated, gold filled and vermeil as distinct descriptions with their own rules. A stamp that matches one of these terms is a clue worth noting, but a stamp can be missing, worn or wrong, and the guides are about how sellers describe goods, not a way to test a piece. Treat a mark as the beginning of your checking.
The Magnet: A Quick Screen
A magnet is cheap and fast, and it works best as an elimination tool. Gold and silver are not attracted to a magnet, so a piece that sticks firmly is not solid gold or solid silver. That helps you pass on a lot of costume pieces and steel components quickly.
The limits matter more than the trick. Many non-precious metals are also not magnetic, so a piece that does not stick is not proven to be precious. Clasps, springs and pin stems inside real jewelry may contain steel, so a pull on one small part tells you less than you think. Test the main body, hold the magnet loosely, and treat the result as one data point.
Acid and Electronic Test Kits
Scratch-and-acid kits compare how a mark left on a testing stone reacts to different liquids. They are a step up from a magnet and are popular for gold, but they come with real cautions. The liquids are corrosive. Follow the kit's instructions and safety data exactly, work in a ventilated area, wear the eye and skin protection the kit recommends, keep liquids away from children and pets, and never mix products. Test only a hidden spot, because the method leaves a mark.
The kit does not examine the whole piece. It samples one tiny area, so a plated surface or a mixed construction can mislead you. Do not use acid on pieces with delicate finishes, stones or enamel, and consider skipping it on anything you suspect is collectible, since a mark can reduce its appeal to buyers.
Electronic testers are a separate category. Some use electrical conductivity to estimate metal type, and they vary in what they measure and how they need to be calibrated. If you buy one, read the maker's manual for what it claims to detect, and compare it against pieces you can verify. No small handheld tool replaces a professional assay or an appraisal.
Gold and Silver Testing Kit
Read the kit's safety instructions first. The liquids are corrosive, and the kit samples one spot only.
Search on Amazon → Search on eBay →As an Amazon Associate, we earn from qualifying purchases at no extra cost to you. We only recommend gear we’d buy ourselves.
A Few Small Extras Worth Having
A small digital scale gives you a weight in grams, which matters for listings and for sellers who sell by weight. Pair it with a soft cloth, a few small trays for sorting, and good light. A polishing cloth is handy for wiping dirt off a stamp before reading it, but go gently, and skip polishing anything that might have a patina worth keeping.
Small Digital Scale for Jewelry
A scale that reads in grams helps with listings. Check the maker's spec sheet for its capacity and increments.
Search on Amazon → Search on eBay →As an Amazon Associate, we earn from qualifying purchases at no extra cost to you. We only recommend gear we’d buy ourselves.
A Simple Order of Operations
- Look first. Use the loupe to read marks and check construction and wear.
- Screen with the magnet. Set aside anything that sticks firmly.
- Weigh and photograph. Record weight and clear photos of the marks.
- Test only if needed. Use a kit on a hidden spot only when the earlier steps leave you unsure and the piece is not delicate.
- Hand off the uncertain. For pieces that matter, a local jeweler or appraiser is the right next step.
Be honest in your listings about what you know. Describe marks as what is stamped, say what you checked, and avoid promising a piece is genuine. Our post on spotting fake designer items uses the same careful approach, and the guide to passing on a good deal is worth a read before you buy anything you cannot verify.
Frequently Asked Questions
Does a magnet test prove gold or silver is real?
No. Gold and silver are not attracted to a magnet, so a strong pull rules a piece out, but many non-precious metals are also non-magnetic. Treat the magnet as a quick screen only.
Are acid test kits safe to use at home?
They contain corrosive liquids, so follow the kit's instructions and safety data, work in a ventilated area, wear the protection it recommends and never mix products.
What does a stamp on jewelry prove?
A stamp is a clue, not proof. Marks can be worn, missing or incorrect, so use them alongside other checks and a professional opinion for valuable pieces.
Do I need a loupe if I use a phone camera?
A loupe is faster in the aisle and good for reading marks in poor light. Phone macro photos are useful for records but are not a substitute for looking closely before you buy.
When should I take a piece to a jeweler?
When a piece looks well made, the marks are unclear, or a purchase decision depends on whether it is precious metal, ask a local jeweler or appraiser.